Re: Need advise for high precision cnc
With those specifications you have moved well out of the hobby class machine into a high precision full on industrial machine. Forget about Gecko, Kmotion, Mesa, and Chinese ball screws. You will need industrial hardware.
First start with a good used 6030 Fadal just to get a solid platform, work envelope, motors, and drives to work with.
Pour a low expansion concrete isolation base for the machine to sit on.
Rebuild the ball screws as needed to get zero backlash.
Rebuild ways as needed.
Install temperature controls in the building to keep the environment at a constant 18°C
Then rip out the controls.
Install 0.5 um resolution linear encoders on all axes.
Install a 4080 Galil motion controller to run the system, and yes, close the loop at the controller.
Calibrate the system using a laser infromenter.
Now you have a chance at actually holding the the specification that you want.
What you are proposing is going to be very expensive. I have two machines in my shop that will hold <+/- 0.01mm consistently, but they also each have about $10,000 in controls upgrades and that's just the hardware cost. Both have a work envelope of about 32x12.5 inches. Your work envelope requirement adds an order of magnitude of difficulty in holding your specs.
Jim Dawson
Sandy, Oregon, USA